The attachment of electrical components such as modules to circuit boards or cards is commonly done by inserting the component leads into holes in the card surface and soldering the junctions. This mode of attachment provides component stand-off which is highly desirable to permit circulation of cooling fluid about the components. As components and circuit cards are reduced in size by the continuing effort to miniaturize electronic packaging, lead and hole dimensions are also made smaller. The leads become less stable and there is greater difficulty in concurrently inserting the multiple leads into the respective holes. The solution to the assembly problem has been to forego lead insertion and attach the component leads to the surface of the circuit lands surrounding the small through holes.
Open circuits, however, frequently occur at the lead-land junctions when components such as modules having many leads are soldered. These open circuits are caused by failure of the solder to bridge the slight gaps between some leads and their respective lands. The gaps are usually due to small differences in the lengths of the leads or warpage of the circuit cards. When soldering is undertaken, the surface tension of the molten solder prevents bridging certain of the gaps resulting in an inoperative assembly and expensive rework. A further disadvantage is that in certain joints the solder may bridge the gaps but fail to produce fillets of adequate cross-section so that fracture of the weaker joints occurs in subsequent field usage.
It is accordingly a primary object of this invention to provide apparatus and method for electrical component attachment insuring that each component lead is in electrical contact with its respective land so that there are no unbridged gaps subsequent to soldering.
A further object of this invention is to provide connecting devices for attaching component leads to circuit lands which adjust to the extent required to eliminate any gaps between the leads and circuit lands.
A further object of this invention is to provide a method by which a plurality of parallel component leads may simultaneously be positioned in electrical contact with respective lands.
Another object of this invention is to provide conductive sleeves for component leads which frictionally engage the leads and are automatically adjusted along the leads to proper positions as the component is brought into position on the circuit card for soldering.
A still further object of this invention is to provide a split sleeve connector of conductive material which is slideable along a component lead to the desired position which is readily solderable to both the lead and circuit land.